Abstract: The present disclosure provides a pair of NMOSFET switches connected in series, an output filter, a control circuit, a boot-strap capacitor and a disabling circuit. A high-side MOSFET switch is coupled to an input voltage. A low-side MOSFET switch is coupled to a ground. The high-side MOSFET switch and the low-side MOSFET switch have complementary duty cycles. The output filter is coupled to the NMOSFET switches to provide an output voltage. The boot-strap capacitor is coupled to the source of the high-side MOSFET switch. The voltage crossing the boot-trap capacitor is for making the gate voltage of the high-side MOSFET switch to be higher than the input voltage. The disabling circuit senses the voltage crossing the boot-strap capacitor, and generates a control signal to control the control circuit for continuously turning off the high-side MOSFET switch when the voltage crossing the boot-strap capacitor is less than a threshold voltage.

Abstract: The present disclosure provides a pair of NMOSFET switches connected in series, an output filter, a control circuit, a boot-strap capacitor and a disabling circuit. A high-side MOSFET switch is coupled to an input voltage. A low-side MOSFET switch is coupled to a ground. The high-side MOSFET switch and the low-side MOSFET switch have complementary duty cycles. The output filter is coupled to the NMOSFET switches to provide an output voltage. The boot-strap capacitor is coupled to the source of the high-side MOSFET switch. The voltage crossing the boot-trap capacitor is for making the gate voltage of the high-side MOSFET switch to be higher than the input voltage. The disabling circuit senses the voltage crossing the boot-strap capacitor, and generates a control signal to control the control circuit for continuously turning off the high-side MOSFET switch when the voltage crossing the boot-strap capacitor is less than a threshold voltage.

Abstract: A fan control circuit for controlling a two-wire or three wire fan in a fan control system includes: a rotational speed detecting module, for detecting a rotational speed of the fan, in order to generate a rotational speed signal; a rotational speed converting module, coupled to the rotational speed detecting module, for converting the rotational speed signal into a first voltage signal; and a feedback control module, coupled to the rotational speed converting module, for generating a fan control signal to control the fan according to the first voltage signal.

Abstract: A delay method for determining an activation time of an output device in a circuit system is disclosed. The delay method includes determining resistance of an over-current flag pull-high resistor of the circuit system, generating a current according to the resistance of the over-current flag pull-high resistor and a voltage drop across the resistor, duplicating the current to generate a division current, drawing the division current from a charging current to determine an activation current of the output device, and determining the activation time point of the output device according to the activation current.

Abstract: A delay method for determining an activation moment of an output device in a circuit system is disclosed. The delay method includes determining resistance of an over-current flag pull-high resistor of the circuit system, generating a current according to the resistance of the over-current flag pull-high resistor and a voltage drop across the resistor, duplicating the current to generate a first mirror current, delaying an enable signal of the circuit system according to the first mirror current to generate a charging activation signal, providing a charging current according to the charging activation signal, and determining the activation moment of the output device according to the activation current.

Abstract: A delay method for determining an activation time of an output device in a circuit system is disclosed. The delay method includes determining resistance of an over-current flag pull-high resistor of the circuit system, generating a current according to the resistance of the over-current flag pull-high resistor and a voltage drop across the resistor, duplicating the current to generate a division current, drawing the division current from a charging current to determine an activation current of the output device, and determining the activation time point of the output device according to the activation current.

Abstract: A delay method for determining an activation moment of an output device in a circuit system is disclosed. The delay method includes determining resistance of an over-current flag pull-high resistor of the circuit system, generating a current according to the resistance of the over-current flag pull-high resistor and a voltage drop across the resistor, duplicating the current to generate a first mirror current, delaying an enable signal of the circuit system according to the first mirror current to generate a charging activation signal, providing a charging current according to the charging activation signal, and determining the activation moment of the output device according to the activation current.